Laravel 5.4 struggling with relationships

I need help with Laravel 5.4 relationships.

I have 4 tables:

users (fileds: id, name, etc.)

profiles (fields: id, user_id, first_name, last_name)

orders (fields: id, user_id, etc.) order_items (fields: id, order_id, product_id, etc.)

A user can have one profile

A profile can have one user

A user can have many orders

An order an have one user

An order can have many items

In the models I have:

User:

public function profile()
{
    return $this->hasOne('App\Profile');
}

public function orders()
{
    return $this->hasMany('App\Order');
}

Profile:

public function user()
{
    return $this->belongsTo('App\User');
}

Order:

public function user()
{
    return $this->hasOne('App\User');
}

public function order_items()
{
    return $this->hasMany('App\OrderItem');
}

orderItem:

public function order()
{
    return $this->belongsTo('App\Order');
}

public function product()
{
    return $this->hasOne('App\Product');
}

I have two questions:

1. When I show an order, I want to show the first_name and last_name columns from the profiles table.

In my controller I did this: $user = User::find($order->user_id);

In my view:

Is there a way to get the name directly in the view and not fetch the user first in the controller?

2.

In my Order model:

When I view the order I want to display all the order items and the product name (product->name) for each item.

I'm very confused and don't know how to do this.

In my controller I tried: 1.

$items = Order::find($order->id)->order_items->with('product');

Got an error: Trying to get property of non-object

2. $items = Order::find($order->id)->order_items;

    foreach($items as $item) {
        echo $item->product->name;
    }

Got an error:

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'products.order_item_id' in 'where clause' (SQL: select * from products where products.order_item_id = 1 and products.order_item_id is not null limit 1)

via Chebli Mohamed